Devaraj Das created HBASE-18214:
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Summary: Replace the folly::AtomicHashMap usage in the RPC layer
Key: HBASE-18214
URL: https://issues.apache.org/jira/browse/HBASE-18214
Project: HBase
Issue Type: Sub-task
Reporter: Devaraj Das
Assignee: Devaraj Das
In my tests, I saw that folly::AtomicHashMap usage is not appropriate for one,
rather common use case. It'd become sort of unusable (inserts would hang) after
a bunch of inserts and erases. This hashmap is used to keep track of call-Id
after a connection is set up in the RPC layer (insert a call-id/msg pair when
an RPC is sent, and erase the pair when the corresponding response is
received). Here is a simple program that will demonstrate the issue:
{code}
folly::AtomicHashMap<int, int> f(100);
int i = 0;
while (i < 10000) {
try {
f.insert(i,100);
LOG(INFO) << "Inserted " << i << " " << f.size();
f.erase(i);
LOG(INFO) << "Deleted " << i << " " << f.size();
i++;
} catch (const std::exception &e) {
LOG(INFO) << "Exception " << e.what();
break;
}
}
{code}
After poking around a little bit, it is indeed called out as a limitation here
https://github.com/facebook/folly/blob/master/folly/docs/AtomicHashMap.md (grep
for 'erase'). Proposal is to replace this with something that will fit in in
the above usecase (thinking of using std::unordered_map).
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